The present invention relates to a motor-driven compressor.
A motor-driven compressor generally has a hermetic terminal. Japanese Unexamined Patent Application Publication No. 2005-307798 discloses a hermetic terminal including a terminal base disposed in a hole formed through an airtight compressor housing of the motor-driven compressor, a conductive member (terminal pin) for electrically connecting an electric motor and an inverter, and an insulating member (glass insulator) for fixing the conductive member to the terminal base while maintaining the insulation of the conductive member from the terminal base. In the airtight compressor housing, a cluster block is connected to the conductive member of the hermetic terminal. The cluster block has a housing which covers a terminal connection between the conductive member and the connecting terminal to which the wire from the electric motor is connected.
When the operation of the motor-driven compressor is stopped, refrigerant gas in the compressor housing is cooled and condensed, and such liquid refrigerant may remain in the compressor housing. If the liquid refrigerant enters into the cluster block housing and the conductive member disposed in the compressor housing is immersed in the liquid refrigerant, the conductive member and the compressor housing are electrically conducted with each other through the liquid refrigerant, so that the conductive member is no more electrically insulated from the compressor housing. When the operation of the motor-driven compressor is started in such condition, current supplied to the conductive member may leak to the compressor housing through the liquid refrigerant.
To solve the above problem, Japanese Patent Publication No. 2001-182655 discloses a motor-driven compressor wherein the conductive member and the insulating member disposed in the compressor housing are coated with the insulating resin. Thus, if the conductive member is immersed in the liquid refrigerant, the coating of the insulating resin increases the insulation distance between the conductive member and the compressor housing, so that leak between the conductive member and the compressor housing is prevented successfully.
According to the above Publications No. 2005-307798 and No. 2001-182655, the conductive member is prevented from being immersed in the liquid refrigerant by sealing clearance between the compressor housing and the cluster housing accommodating the conductive member or the insulating resin. This helps to prevent the conductive member, the core wire of the wire assembly and the terminal connection from electrically conducting with the compressor housing through the liquid refrigerant, so that the insulation resistance between the compressor housing and the conductive member, the core wire of the wire assembly and the terminal connection may be improved.
Sealing between the cluster housing or the insulating resin and the compressor housing airtightly closes the cluster housing or insulating resin. If liquid refrigerant is accumulated and remained in the compressor housing, pressure difference is created between the cluster housing or the insulating resin and the compressor housing. In this case, there is a fear that the cluster housing and the insulating resin cannot resist the pressure difference.
Any hole formed through the cluster housing or the insulating resin for communication between the cluster housing or the insulating resin and the compressor housing may equalize the pressure between the cluster housing or the insulating resin and the compressor housing. However, current supplied to the conductive member is leaked to the compressor housing from the hole through the liquid refrigerant flowed into the cluster housing or insulating resin, and there is a fear that the conductive member, the core wire of the wire assembly and the terminal connection fail to be insulated from the compressor housing.
The present invention is directed to providing a motor-driven compressor that improves insulation resistance between the compressor housing and the conductive member in the cluster housing, the core wire of the wire assembly and the terminal connection while maintaining the pressure in the cluster housing substantially the same as the pressure in the compressor housing.